This invention generally relates to rollers. More particularly, the present invention pertains to a ring which can be used as an outer race or as a bearing race in a roller, and to a method for producing the ring.
Rollers typically include a roller bearing having an inner race, an outer race, roller bodies and a bearing race concentrically surrounding the outer race. The bearing race can be omitted, with the outer race performing the function of the bearing race. One context in which rollers are used is in forklifts in which the fork rolls along rollers positioned on the lifting mast. In this application and a number of others, the rollers are exposed to heavy loads. Thus, high bending stresses occur at the outer race and the bearing race, especially when the main load is introduced into the region between successive or adjacently arranged roller bodies. Both the outer race and the bearing race must be designed to absorb the incident bending stresses without being damaged. As a general rule, this typically means fabricating the outer race and the bearing race so that they possess relatively significant material thicknesses. This of course undesirably increases the cost and weight associated with the resulting products.
In light of the foregoing, a need exists for a roller, particularly an outer race or bearing race for a roller, that is capable of absorbing incident bending stresses during operation without significantly increasing the weight.
Generally speaking, the present invention provides an outer ring of a roller with the outer ring being adapted to form either the outer race or the bearing race of the roller. The outer ring is advantageously constructed to produce internal mechanical stresses that counteract the bending stresses occurring during operation of the roller so that the outer ring and the roller can be designed for a reduced load in an economical and light weight manner. The stresses are created by virtue of at least one annular reinforcement body that is press-fitted into a recess in the outer ring of the roller, and whose internal radius is smaller than the internal radius of the recess. The manner in which the reinforcement body is introduced into the recess of the outer ring is preferably selected so that the radially inwardly oriented surface of the reinforcement body is joined materially to the outer ring so that the stresses generated in the reinforcement body, for instance as a consequence of the press fit, are transmitted to the outer ring. The material joining can be done by forging, welding, and friction welding. If the stresses are not excessively high, adhesive bonding can also be employed. Also, the reinforcement body can be poured into the recess in liquid form and during shrinkage of the reinforcement body that ensues in the cooling phase after solidification, stresses occur in the outer ring in this version as well.
One aspect of the present invention involves a roller that includes an annular inner race, an annular outer ring, and a plurality of roller bodies positioned radially inwardly of the annular outer ring and radially outwardly of the annular inner race for rolling along a radially outwardly facing surface inner race. The outer ring is provided with at least one annular recess in which is disposed an annular reinforcement body which subjects the region of the outer ring located radially inside the reinforcement body to mechanical stresses. A side of the reinforcement body facing toward the region that is subjected to such stresses is materially joined to the outer ring.
According to another aspect of the invention, an outer ring is provided for a roller that also includes an inner race and a plurality of roller bodies disposed radially outwardly of the inner race for rolling on the outer peripheral surface of the inner race. The outer ring is comprised of an annular ring provided with at least one annular recess in which is disposed an annular reinforcement body that subjects the region of the annular ring located radially inwardly of the reinforcement body to mechanical stresses. The side of the reinforcement body facing towards the region of the annular ring that is subjected to such mechanical stresses is materially joined to the annular ring.
Another aspect of the present invention involves a method for producing an outer ring for a roller that also includes an inner race and a plurality of roller bodies disposed radially outwardly of the inner race for rolling on the outer peripheral surface of the inner race. The method involves machining at least one annular recess into an annular ring, positioning in the recess a reinforcement body that subjects the region of the annular ring radially inside the reinforcement body to mechanical stresses during operation of the roller, and materially joining the side of the reinforcement body facing the region subjected to such stresses to the annular ring.